Presentation on theme: "Bacteria and gut health"— Presentation transcript:
1 Bacteria and gut health Departmet of Food BiosciencesThe University of ReadingBacteria and gut healthGlenn GibsonINYS Workshop. 30th Nov 2006
2 What are bacteria? Single cell organisms No nucleus but very clever! Reproduce by splitting in halfRound, rod, spiral, comma, square99.9% are “friendly”5,000,000,000,000,000,000,000,000,000,000 bacteria exist on the Planet EarthThey regenerate 1/2 million times quicker than humans
3 Where do they come from? Birth: initial colonisers First week: conditionsfavourable for growthBreast fed: bifidobacteria predominateFormula fed: similar profile to days 4-7Key development stages occur
4 Microflora of the stomach Low pHTransit time ca. 30 minutesHCl + pepsinColonisers need to invade the mucosal layerNumbers are lowH. pylori is notorious
5 Microflora of the small intestine Transit time is 2-4hThe organ is a long narrow tubeBile salts and pancreatic secretions affect colonisation by the indigenous floraTypical numbers are (only!) around 1 million per mL contents
6 Microflora of the Large Intestine 150cm in lengthTypical transit time of 24-72hThe most heavily colonised organ in the human bodyAntimicrobial intake, stress, poor diet and living conditions all affect the flora compositionUp to 1000 speciesMost of the bacteria in your body (1,000,000,000,000,000) are here
7 2 4 11 Harmful/pathogenic effects Health promoting functions / effects Ps. aeruginosaPathogenic, including production of toxinsProteusNo/g Faeces (log10)StaphylococciClostridia4Inhibition of growth of harmful bacteriaProduction of carcinogensVeillonellaeEnterococciStimulation of immune functionsE. coliIntestinal putrefactionLactobacilliStreptococciAid in digestion or absorption of nutrientsEubacteriaBifidobacteriaBacteroidesSynthesis of vitamins11(Gibson & Roberfroid, J. Nutr. 125, 1995)
8 What are probiotics? Live microbes in the diet Do the products match up?Delivery of probiotic bacteria to the lower gut is required>80 positive human trials are reportedGastric JuicesBile
9 or, target the indigenous (prebiotics) “functional”food3. selective effect2. enters the largegut
10 Reported prebiotics in use OligosaccharideSoybean oligosaccharidesIsomalto-oligosaccharidesLactosucroseGluco-oligosaccharidesXylo-oligosaccharidesLactuloseGalacto-oligosaccharidesInulinFructo-oligosaccharides
11 31 Volunteers fed Prebiotic Biscuits for 21 days Active biscuits () Control biscuits ()
12 Enhancing functionality Distally targeted activitiesAnti-adhesive effectsSpecies level changesActivities at low dosage without side effectsMaintenance of effects in real foodsHealth effects
13 Health effects of gut bacteria Conditions other than inside the gut (e.g. bone health, eczema)Bowel and stomach cancerInflammation of the colon (IBS, IBD)Gut infections (e.g. food poisoning)
14 How does it work? Prebiotics in infant monkey feed stopped E. coli infectionIt was seen that the “good”bacteria had grown up tocause this resultMonkeys and humans are99.6% the same
15 Prebiotic foods researched and developed at UoR Yoghurts and fermented milksHealth drinks, spreadsInfant and weaning foodsCerealsBiscuitsJuicesPet foodFarm animals
16 ASDs and the human gut microflora Some clinical reports show that some children with ASDs may suffer from intestinal dysfunction presenting various different symptoms:DiarrhoeaConstipationExcess windAbdominal discomfortBloated “stomach”No direct evidence of human gut microflora imbalance.
17 Intestinal Bacteria in ASDs Clostridia and ASDsBolte (1998)Clostridium tetani suggested as pathogenic in ASDs - production of neurotoxins absorbed from gut leading cognitive abnormalities.Sandler et al (2000)Reported on the use of oral vancomycin therapy in ASDs. Significant improvements with antibiotic treatment were noted but with a short term benefit.
18 Intestinal Bacteria in ASDs Finegold et al (CID 2002) (Bacteriology in Reading)Improved symptomology with oral vancomycinStudy compared species found in the stools of regressive autistic children and control children in USA.Higher number in autistic group for clostridial counts.Autistic children yielded 9 species of clostridia not found in control group in stool samples.Overall counts of clostridia were higher in the stools of the autistic children – through culture methods.
19 Theoretical Overview Can imbalances in the gut microflora contribute: towards certain symptoms of autism?towards gastrointestinal problems in autism?Particular gut bacteria may be important.Control of these species maybe of relevance.
20 Aim of the studyCharacterisation of the gut microflora of autistic and Autistic Spectrum disorders (ASDs) SubjectsBuilds upon work with USA autistic childrenEvaluate the need and monitor the effectiveness of probiotic strategies in the treatment and alleviation of GI symptoms (some already used)
21 ApproachesProfile of human gut bacteria in ASDs subjects using molecular based techniques:Quantitative studyFluorescent in situ Hybridisation (FISH)Qualitative studyDGGE separation of amplified PCR productsComparison to gut flora of healthy children, adults and siblings.To identify a probiotic that has anti-bacterial activity against relevant microbes.Questionnaire – for retrospective correlation of bacterial profile and characteristics (Gastrointestinal function, Diet, Medical history).
22 Subjects Number of children taking part in the study: - 60 with confirmed diagnosis- 11 females and 49 MalesPatients had gastrointestinal symptoms, such as diarrhoea and constipation, and were on gluten and casein-free diets.Control groups:- 10 non ASDs children- 10 siblings of ASD children- 50 adults
24 Differences in bacterial groups (cf. Children):
25 Bacteriology resultsClostridia counts from autistic subjects were higher in comparison with the control groupsNo major change in other bacterial groups but overall differences were proven (due to clostridia).In our hands, such a clostridial predominance has not been hitherto observed in any other study group
26 Inhibitory activity of different probiotics against Clostridium spp. Inhibitory activity tested using co-culture.Test for anti-pathogenic activity against clostridia.Different strains of Lactobacillus and Bifidobacterium spp. were selected.Extrapolate to other clostridia as based upon DGGE data
27 ResultsFiltered broths from L. plantarum showed inhibitory effects upon the growth of clostridia.L. plantarum broth did not lose the inhibitory activity after being boiled for 10 min, and showed stronger inhibition.The strain has had its entire genome sequencedAll the other probiotic strains tested showed no inhibition of the clostridia.
28 Link between gut function and ASDs ? Unusual gut microflora components - release of toxic compoundsSystemic effectsAltered gut functionProbiotic/prebiotic interventionUndefined interactionGut DysbiosisOvergrowth of bacteria such as clostridiaGut floraacquisitionAlterations in gut microfloraGI problems
29 Experimental objectives To study the:Effect of L. plantarum WCFS1 on autisticgut microflora. Packaged in BelgiumImpact on gastrointestinal health.Psychological impact on children (behaviour, communication, emotional problems)
30 Inclusion/exclusion criteria Inclusion Criteria:Diagnosis of ASDAge 4-16 years of ageSigned consent formExclusion Criteria:Intake of other probiotics or prebioticsAdministration of antibioticsIf the child is Involved in other similar study or involving an experimental drug/medication.
31 Recruitment Step 1 Through databases - 166 Step 2 Through advertising/ media - unknownTotal responses: Yes – 211. No – 72.Step 3 Exclusion Criteria 1: distance to Reading 116Step 4 Agreement to experimental protocol: 85Step 5 Exclusion criteria 2: 69Step 6 Final consent – 6223 withdrew before commencing the interventionFinal number – 39(Time 7 months)
32 Trial design Double blind placebo-controlled, randomised crossover studyGroup 1WashoutProbioticPlaceboGroup 2WashoutPlaceboProbiotic-7 days21 days21 days21 days21 days123456Samples 1-6 taken for analysis
33 Analysis Samples - molecular analysis by FISH Volunteer Diary - assess tolerance of probiotic, stool frequency and consistency, abdominal pain, intestinal bloating, flatulence.Psychology study - Assess psychological impact of probiotic administration through a standardised “Development Behaviour Checklist ”.
35 Volunteer diaries:Improved in stool consistency (formed stools) (P=0.006) and reduced flatulence (P=0.01).Various differences in abdominal pain (P=0.10) and intestinal bloating ((P=0.055)Total behaviour scorings showed a non-significant difference in the interventions but the probiotic gave reductions. Both placebo and probiotic gave significant reductions cf. pre-treatment (P<0.05)Comments from the parents shows that the probiotic has helped their general well being and gut symptoms in particular17 volunteers completed the study(although 22 provided data for analysis)
36 Parent´s observations Treatment period:More calm, relaxed, not stressed, no mood change, contentImproved ability to listen & concentrateHighest grades at school so farBetter formed stoolsWashout Period:Heartbreaking to see the improvements deterioratingLoose stools & undigested food particlesAbdominal painDepressed moodPoor grades at school
37 Preliminary conclusions From FISHLactobacillus/enterococci group higher in active (P<0.05) compared to placebo. Small effect on clostridiaFrom DiariesGeneral bowel function of the children improved‘Cautious optimism’ but overall the trial failed